[docs] [issue16544] Add external link to ast docs

New submission from Andrew Svetlov: http://greentreesnakes.readthedocs.org/en/latest/index.html is excellent and comprehensive documentation for ast tree structures. It would be nice to incorporate that docs into stdlib documentation, but adding *see also* section is good enoigh as first step. ---------- assignee: docs@python components: Documentation keywords: easy messages: 176239 nosy: asvetlov, docs@python priority: normal severity: normal stage: needs patch status: open title: Add external link to ast docs versions: Python 3.3, Python 3.4 _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue16544> _______________________________________